| 1. |
- Andersson, I. M., et al.
(författare)
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Impact of protein surface coverage and layer thickness on rehydration characteristics of milk serum protein/lactose powder particles
- 2019
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 561, s. 395-404
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Tidskriftsartikel (refereegranskat)abstract
- Spray-dried powders were produced from milk serum protein concentrate and lactose in varying ratios, and the rehydration characteristics of the powders were evaluated. The dissolution rate was estimated with a flow-cell based technique, and the external and internal distribution of the powder components were evaluated with X-ray photoelectron spectroscopy and confocal Raman microscopy, respectively. The surface of the powder particles is more or less covered by a thin protein layer. A phase segregation between protein and lactose is observed in the interior of the particle resulting in a protein rich layer in the vicinity of the surface. However, the protein layer in the vicinity of the particle surface tends to become thinner as the bulk protein concentration increases in the powders (from 10 to 60% w/w). The time for the spontaneous imbibition to occur show a linear correlation with the protein surface coverage. The dissolution rate of powders containing 0.1% w/w protein is around 60 times faster than for a powder containing 1% w/w protein but the dissolution rate of powders containing 1% and 100% w/w differ only by a factor of 2. Thus, it is suggested that the outer protein layer becomes denser at the interface as the protein content increases in the powders, thereby causing poorer rehydration characteristics of the powders (especially for low protein concentrations 0.1–1% w/w). This insight has relevance for the formulation of whey protein powders with improved rehydration characteristics. © 2018 Elsevier B.V.
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| 2. |
- Andersson, I. M., et al.
(författare)
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Impact of surface properties on morphology of spray-dried milk serum protein/lactose systems
- 2018
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 85, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated milk serum protein concentrate/lactose systems with varying ratios and how the morphology of the spray-dried particles of these systems could be described by the surface properties of the feed as well as the protein surface coverage of the particles. An extrapolation of the surface pressure of the feed to 0.3 s, the approximate time for molecular diffusion in an atomised droplet in the spray-dryer, showed a relationship with the particle morphology. At low protein concentrations (<1%), the particles were almost totally smooth. At higher protein concentrations (≥1%), the particles became dented and ridged, and these tended to become deeper and thicker as the protein concentration increased. It is suggested that the surface pressure of the feed at low protein concentrations is the most prominent surface property, whereas the modulus of elasticity seems to be the most prominent surface property for particle surface deformation at higher protein concentrations.
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| 3. |
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| 4. |
- Badal Tejedor, Maria, 1986-, et al.
(författare)
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AFM Colloidal Probe Measurements Implicate Capillary Condensation in Punch-Particle Surface Interactions during Tableting
- 2017
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 33:46, s. 13180-13188
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Tidskriftsartikel (refereegranskat)abstract
- Adhesion of the powders to the punches is a common issue during tableting. This phenomenon is known as sticking and affects the quality of the manufactured tablets. Defective tablets increase the cost of the manufacturing process. Thus, the ability to predict the tableting performance of the formulation blend before the process is scaled-up is important. The adhesive propensity of the powder to the tableting tools is mostly governed by the surface-surface adhesive interactions. Atomic force microscopy (AFM) colloidal probe is a surface characterization technique that allows the measurement of the adhesive interactions between two materials of interest. In this study, AFM steel colloidal probe measurements were performed on ibuprofen, MCC (microcrystalline cellulose), α-lactose monohydrate, and spray-dried lactose particles as an approach to modeling the punch-particle surface interactions during tableting. The excipients (lactose and MCC) showed constant, small, attractive, and adhesive forces toward the steel surface after a repeated number of contacts. In comparison, ibuprofen displayed a much larger attractive and adhesive interaction increasing over time both in magnitude and in jump-in/jump-out separation distance. The type of interaction acting on the excipient-steel interface can be related to a van der Waals force, which is relatively weak and short-ranged. By contrast, the ibuprofen-steel interaction is described by a capillary force profile. Even though ibuprofen is not highly hydrophilic, the relatively smooth surfaces of the crystals allow "contact flooding" upon contact with the steel probe. Capillary forces increase because of the "harvesting" of moisture - due to the fast condensation kinetics - leaving a residual condensate that contributes to increase the interaction force after each consecutive contact. Local asperity contacts on the more hydrophilic surface of the excipients prevent the flooding of the contact zone, and there is no such adhesive effect under the same ambient conditions. The markedly different behavior detected by force measurements clearly shows the sticky and nonsticky propensity of the materials and allows a mechanistic description.
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| 5. |
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| 6. |
- Badal Tejedor, Maria, 1986-, et al.
(författare)
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Milling induced amorphisation and recrystallization of α-lactose monohydrate
- 2018
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 537:1-2, s. 140-147
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Tidskriftsartikel (refereegranskat)abstract
- Preprocessing of pharmaceutical powders is a common procedure to condition the materials for a better manufacturing performance. However, such operations may induce undesired material properties modifications when conditioning particle size through milling, for example. Modification of both surface and bulk material structure will change the material properties, thus affecting the processability of the powder. Hence it is essential to control the material transformations that occur during milling. Topographical and mechanical changes in surface properties can be a preliminary indication of further material transformations. Therefore a surface evaluation of the α-lactose monohydrate after short and prolonged milling times has been performed. Unprocessed α-lactose monohydrate and spray dried lactose were evaluated in parallel to the milled samples as reference examples of the crystalline and amorphous lactose structure. Morphological differences between unprocessed α-lactose, 1 h and 20 h milled lactose and spray dried lactose were detected from SEM and AFM images. Additionally, AFM was used to simultaneously characterize particle surface amorphicity by measuring energy dissipation. Extensive surface amorphicity was detected after 1 h of milling while prolonged milling times showed only a moderate particle surface amorphisation. Bulk material characterization performed with DSC indicated a partial amorphicity for the 1 h milled lactose and a fully amorphous thermal profile for the 20 h milled lactose. The temperature profiles however, were shifted somewhat in the comparison to the amorphous reference, particularly after extended milling, suggesting a different amorphous state compared to the spray-dried material. Water loss during milling was measured with TGA, showing lower water content for the lactose amorphized through milling compared to spray dried amorphous lactose. The combined results suggest a surface-bulk propagation of the amorphicity during milling in combination with a different amorphous structural conformation to that of the amorphous spray dried lactose. The hardened surface may be due to either surface crystallization of lactose or to formation of a low-water glass transition.
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| 7. |
- Badal Tejedor, Maria, et al.
(författare)
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Tablet mechanics depend on nano and micro scale adhesion, lubrication and structure
- 2015
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 486:1-2, s. 315-323
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Tidskriftsartikel (refereegranskat)abstract
- Tablets are the most convenient form for drug administration. However, despite the ease of manufacturing problems such as powder adhesion occur during the production process. This study presents surface and structural characterization of tablets formulated with commonly used excipients (microcrystalline cellulose (MCC), lactose, mannitol, magnesium (Mg) stearate) pressed under different compaction conditions. Tablet surface analyses were performed with scanning electron microscopy (SEM), profilometry and atomic force microscopy (AFM). The mechanical properties of the tablets were evaluated with a tablet hardness test. Local adhesion detected by AFM decreased when Mg stearate was present in the formulation. Moreover, the tablet strength of plastically deformable excipients such as MCC was significantly decreased after addition of Mg stearate. Combined these facts indicate that Mg stearate affects the particle-particle bonding and thus elastic recovery. The MCC excipient also displayed the highest hardness which is characteristic for a highly cohesive material. This is discussed in the view of the relatively high adhesion found between MCC and a hydrophilic probe at the nanoscale using AFM. In contrast, the tablet strength of brittle materials like lactose and mannitol is unaffected by Mg stearate. Thus fracture occurs within the excipient particles and not at particle boundaries, creating new surfaces not previously exposed to Mg stearate. Such uncoated surfaces may well promote adhesive interactions with tools during manufacture.
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| 8. |
- Boge, Lukas, et al.
(författare)
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Freeze-dried and re-hydrated liquid crystalline nanoparticles stabilized with disaccharides for drug-delivery of the plectasin derivative AP114 antimicrobial peptide
- 2018
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 522, s. 126-135
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Tidskriftsartikel (refereegranskat)abstract
- Liquid crystalline nanoparticles (LCNPs), e.g. cubosomes and hexosomes, are receiving more and more attraction as drug delivery vehicles. Dry powder formulation that forms LCNPs upon hydration can be advantageous to make new routes of administration accessible. In this work, we investigate use of three disaccharides (lactose, trehalose and sucrose) as protective matrices for glycerol monooleate based LCNP forming powders produced by freeze-drying. Phase behavior, particle size and size distributions at the different preparation steps were monitored by small angle x-ray scattering (SAXS) and dynamic light scattering (DLS). Particle appearance was imaged by cryogenic transmission electron microscopy (cryo-TEM). Moreover, the therapeutic relevant antimicrobial peptide AP114 (plectasin derivative) was incorporated in the formulations. Peptide encapsulation and release as well as in vitro antibacterial effect were investigated. Results showed that all freeze-dried powders did form particles with liquid crystalline structure upon hydration. However, a phase transition from the bicontinuous cubic Pn3m to the reversed hexagonal was observed, as a consequence of sugar addition and the freeze-drying procedure. Data indicates that trehalose is the preferred choice of lyo-protectant in order to maintain a mono-modal particle size distribution. In addition, antimicrobial activity of AP114-containing formulations was found to be highest for the formulation containing trehalose. The release kinetics of AP114 from the nanoparticles was strongly affected by the dimensions of the hexagonal phase. Larger dimension of the hexagonal phase, significantly improved the release of AP114 and antimicrobial activity of the formulation.
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| 9. |
- Both, E M, et al.
(författare)
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Morphology development during single droplet drying of mixed component formulations and milk
- 2018
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Ingår i: Food Research International. - : Elsevier BV. - 0963-9969 .- 1873-7145. ; 109, s. 448-454
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Tidskriftsartikel (refereegranskat)abstract
- We report on the influence of selected components and their mixtures on the development of the morphology during drying of single droplets and extend the results to the morphology of whole milk powder particles. Sessile single droplet drying and acoustic levitation methods were employed to study single droplet drying. The influence of carbohydrates (lactose and maltodextrin DE12) and proteins (micellar casein or whey protein) on morphology development is very different, since upon concentration protein systems will jam and undergo a colloidal glass transition, whereas carbohydrate systems will gradually increase in viscosity as a consequence of the concentration. Whey protein gives relatively rigid shells due to jamming of the "hard sphere" proteins, while casein micelles behave as "soft spheres" that can deform after jamming, which gives flexibility to the shell during drying. The influence of the carbohydrates on the final morphology was found much larger than the influence of the proteins. Caseins influenced morphology only in mixtures with lactose at higher concentrations due to its high voluminosity. Similar observations were done for whole milk, where fat appeared to have no influence. With maltodextrin the influence of the casein was again observed in the shape and smoothness of wrinkles. Both sessile and levitated droplet drying methods provide a similar and consistent view on morphology development.
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| 10. |
- Dahlenborg, Hanna, et al.
(författare)
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Effect of particle size in chocolate shell on oil migration and fat bloom development
- 2015
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 146, s. 172-181
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Tidskriftsartikel (refereegranskat)abstract
- The effects of chocolate shell particle size were investigated by means of its influence on rate of oil migration and fat bloom development. The particle size of the non-fat particles in the chocolate, i.e. sugar and cocoa particles was varied between 15, 22 and 40 mu m. A novel set of analytical techniques was used and by combining migration results with surface topology results clear differences could be observed between the samples. At 23 degrees C storage the samples with a particle size of 15 mu m showed higher rate of oil migration and, further, the earliest development of fat bloom at the surface. This could be observed both macroscopically and microscopically. Thus, it appears as a larger specific surface area of the nonfat particles facilitates migration of filling oil, possibly due to a more heterogeneous and coarser crystal network with higher permeability. Molecular diffusion cannot explain the level of oil migration observed and, thus, convective flow is assumed to be an important contribution in addition to the molecular diffusion. (C) 2014 Elsevier Ltd. All rights reserved.
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